The focus of the research proposed here is the nature of the chemotactic defect seen in patients with Localized Juvenile Periodontitis (LJP). Recent studies in our laboratory have revealed a depletion of a 110,000 MW protein (P110) from the surface of LJP neutrophils. This finding has importance as a probe for subcellular, molecular biological studies of neutrophil function and as a marker for epidemiologic studies. We propose to use monoclonal antibody to P110 to cross-sectionally evaluate the prevalence of P110 deficiency in LJP, adult periodontitis and normal controls. For molecular biological studies, P110 will be isolated and biochemically characterized; and the subcellular location of P110 other than the surface membrane will be determined for LJP and normal neutrophils. Previous studies have demonstrated reduced chemotactic factor receptors on the surface of LJP neutrophils. To further assess the surface characteristics of the LJP neutrophil, other ligands will be used as probes of membrane structure. Ligands to be used will include FMLP, C5a, C3b, ConA, WGA, IgG, IgA and anti-P110 antibody. These ligands will be used to determine if functionally non-related ligands will affect neutrophil function in vitro; to assess the surface binding characteristics of these membrane probes to LJP and normal neutrophils and to determine the possible role in up or down regulation of surface components of each probe of membrane structure in order to further characterize the dynamics of receptor expression and function. The long range goal of these investigations is to further our cell knowledge of the structural and functional relationships of the inflammatory process, by defining the complex interactions between the neutrophil and its environment. LJP patients provide a study model for compromised neutrophil function in which the defect is homogenous among patients. It is anticipated that the use of structural probes will further clarify the mechanisms involved which manifest as altered functional capabilities of the LJP neutrophil.